Tractors having bulldozer blades and, in particular, cushioned push blades, have been subjected to the problem that the loads on the blade may possibly lift the front of the tractor which may reduce the effectiveness of the push being administered by the tractor. Also, the mounting of some blades to the tractor frame have been such as to weaken the tractor frame.
In U.S. Pat. No. 3,279,105 in the name of K. J. Kolinger et al, issued Oct. 18, 1966, a bulldozer blade has a pair of arms pivoted to the tractor frame near the lower front corner of said tractor frame. In addition, spring-cushioning arrangements are provided for the upper corners of the blade which are connected to the tractor frame near the upper corners thereof. This arrangement may provide force for pushing upwardly against the front of the frame of the tractor which could lift the front of the frame of the tractor relative to the tracks reducing the effectiveness of the push.
U.S. Pat. No. 3,487,884 in the name of H. Volberding, issued Jan. 6, 1970, provides a bulldozer blade wherein arms extend from the bottom corners of the blade to a bracket hanging down from the midportion of the frame of the tractor. The brackets are welded, bolted, or otherwise secured to the tractor frame. The upper portions of the blade are connected to the forward corners of the tractor frame. The connections of the brackets supporting the arms on the frame may weaken the frame that could result in failure of the support for the blade assembly.
U.S. Pat. No. 3,521,713 in the name of D. J. Spanjer et al, issued July 28, 1970, shows a blade mounted to a pivoted bracket projecting downward from the frame of the vehicle with the upper portion of the bracket being movable by hydraulics. Here the forces on the blade may lift the front of the tractor during a push. In addition, the attachment of the bracket to the vehicle may weaken the vehicle frame.
U.S. Pat. No. 3,809,167 in the name of Lawrence James Glider, issued May 7, 1974, shows a blade pivoted directly to the frame of the vehicle on the forward portion of the frame, such that pressure on the blade may lift the front of the vehicle which may reduce the effectiveness of the push.
All of these patents suffer the disadvantages that they either may cause the front of the tractor to be lifted under the loading applied to the blade, or due to the way they are attached to the tractor frame, they may weaken the tractor frame causing premature failure.